My questions can best be explained by giving a senario. I got married on July 15, 2000. My wife sold some stock for a loss before we were married earlier in the year. I sold some stock for a gain before we were married also earlier in the year and then some other stock for a gain after we were married. If we file jointly can I use her losses to offset all of my gains.

Yes. Your joint gains and losses will all be reported on a single schedule D (since you said you plan to file jointly) and netted against each other. For more details on the netting process, there is an article on it in the FAQ.